High sensitive fiber strain sensor

A fiber-optics strain sensor based on the composite structure of tapered fiber and fiber Fabry-Pérot(F-P) interferometer was proposed and experimentally demonstrated, which comprised 2 strain sensitive regions, the tapered region formed by single mode fiber taper and the F-P cavity based on the quarts capillary tube. The propagation process of light waves in the sensor was analyzed theoretically, and the light intensity transfer function was obtained. As the cladding high-order mode excited by tapered fiber participated in interference, the interference spectrum of sensor had modulation characteristics.The interference spectrum of sensor was obtained by experiment and the independent measurement was realized by analyzing the resonant wavelength shift or extinction ratio change. Experimental results indicate that the proposed sensor presents a sensitivity of 14.6 pm/με in the measurement range from 0 to 500 με Using the modulated interference spectrum formed by the tapered fiber induced mode interference and the double-beam interference of the F-P cavity to conduct strain sensing, the strain sensitivity is high, and 2 kinds of independent strain detection methods (resonant wavelength and extinction ratio detection) can be provided.